Nonunique UPGMA clusterings of microsatellite markers.

Agglomerative hierarchical clustering has become a common tool for the analysis and visualization of data, thus being present in a large amount of scientific research and predating all areas of bioinformatics and computational biology. In this work, we focus on a critical problem, the nonuniqueness of the clustering when there are tied distances, for which several solutions exist but are not implemented in most hierarchical clustering packages. We analyze the magnitude of this problem in one particular setting: the clustering of microsatellite markers using the Unweighted Pair-Group Method with Arithmetic Mean. To do so, we have calculated the fraction of publications at the Scopus database in which more than one hierarchical clustering is possible, showing that about 46% of the articles are affected. Additionally, to show the problem from a practical point of view, we selected two opposite examples of articles that have multiple solutions: one with two possible dendrograms, and the other with more than 2.5 million different possible hierarchical clusterings.

Population genetic structure of tropical bed bug (Hemiptera: Cimicidae) populations and their breeding pattern in Iraq.

A study was conducted to investigate the population genetic structure and breeding pattern of 140 tropical bed bugs, Cimex hemipterus (F.) (Hemiptera: Cimicidae), collected from 14 infested sites in major cities in Iraq. The samples were genotyped using a set of 7 polymorphic microsatellite markers. High genetic variety was seen among populations, with an average of 2-9 alleles per locus. The number of alleles across 7 microsatellite loci was between 6 and 18. There was a notable disparity in the alleles per loci when comparing the overall population to those within it. The overall population exhibited an average observed heterozygosity of 0.175 and an average expected heterozygosity of 0.730. Among the population, the average observed heterozygosity was 0.173, while the average expected heterozygosity was 0.673. Analysis of molecular variance (AMOVA) revealed that 93% of the genetic variability was within the populations, and 7% was among them. The genetic differentiation coefficient (FST = 0.045), indicates a low degree of genetic differentiation and a high degree of inbreeding (FIS = 0.761), as indicated by notably significant positive inbreeding coefficients. Admixed individuals were revealed using STRUCTURE and neighbor-joining phylogenetic trees, demonstrating moderate gene flow between populations and a lack of genetic structure in the regional groups. Thus, both active dispersion and human-mediated dispersion possess the potential to influence the low population genetic structure of tropical bed bug C. hemipterus populations in Iraq, which can have implications toward tropical bed bug and management strategies.

Detection of putative loci affecting milk yield in Turkish Awassi sheep using microsatellite markers.

On the basis of comparisons between bovine and ovine genome mapping information, the aim of the study was to analyze the genetic diversity of selected DNA microsatellites from the bovine genome and to investigate their correlation with the average daily milk yield in Awassi sheep. 18 informative microsatellite markers were selected from the significant QTL regions affecting milk yield identified in the bovine genome in previous studies. The selected microsatellite markers were then amplified by PCR as reciprocal amplifications on the genomic DNA of Awassi sheep, with standard daily milk yield records. Thus, in this study, 18 microsatellite markers associated with milk yield in the bovine genome were examined for both determination of genetic polymorphism within the flock and the effects of marker loci on average daily milk yield in Awassi sheep. Allele frequencies of markers were determined based on the results of fragment analysis. The analysis of variance showed that the 123 bp allele at the marker locus BMS1341 on BTA2 significantly influenced the average daily milk yield of Ivesi sheep (P < 0.01). On the other hand, the BMS381 locus with a 115 bp allele on BTA2, the MCM140 locus with a 185 bp allele on BTA6, the BMS2721 locus with a 155 bp allele, the BM1237 locus with 174 and 180 bp alleles on BTA7, and finally, the BMS1967 locus with a 117 bp allele, the BM4208 locus with 176 and 182 bp alleles, and the INRA locus with a185 bp allele on BTA8 showed moderately significant effects on the average daily milk yield of Ivesi ewes (P < 0.05).

Development of Genetic Markers for Sex and Individual Identification of the Japanese Giant Flying Squirrel (Petaurista leucogenys) by an Efficient Method Using High-Throughput DNA Sequencing.

DNA markers that detect differences in the number of microsatellite repeats can be highly effective for genotyping individuals that lack differences in external morphology. However, isolation of sequences with different microsatellite repeat numbers between individuals has been a time-consuming process in the development of DNA markers. Individual identification of Japanese giant flying squirrels (Petaurista leucogenys) has been challenging because this species is arboreal and nocturnal and exhibits little to no morphological variation between individuals. In this study, we developed DNA markers for sex and individual identification of this species by an efficient method using high-throughput DNA sequence data. Paired-end 5 Gb (2 × 250 bp) and 15 Gb (2 × 150 bp) genome sequences were determined from a female and a male Japanese giant flying squirrel, respectively. We searched SRY and XIST genes located on Y and X chromosomes, respectively, from high-throughput sequence data and designed primers to amplify these genes. Using these primer sets, we succeeded to identify the sex of individuals. In addition, we selected 12 loci containing microsatellites with different numbers of repeats between two individuals from the same data set, and designed primers to amplify these sequences. Twenty individuals from nine different locations were discriminated using these primer sets. Furthermore, both sex and microsatellite markers were amplified from DNA extracted non-invasively from single fecal pellet samples. Based on our results for flying squirrels, we expect our efficient method for developing non-invasive high-resolution individual- and sex-specific genotyping to be applicable to a diversity of mammalian species.

Genetic diversity and phylogenetic relationship estimation of Shanxi indigenous goat breeds using microsatellite markers.

The objective of this study was to assess the genetic diversity, phylogenetic relationship and population structure of five goat breeds in Shanxi, China. High genetic diversities were found in the five populations, among which, Licheng big green goat (LCBG) has the highest genetic diversity, while Jinlan cashmere goat (JLCG) population has the lowest genetic diversity. Bottleneck analysis showed the absence of recent genetic bottlenecks in the five goat populations. Genetic differentiation analysis shows that the closest genetic relationship between LCBG and LLBG (Lvliang black goat) was found, and the genetic distance between JLCG and the other four populations is the largest. The population structure of JLCG is different from the other four populations with K = 2, while LCBG and LLBG have high similarity population structure as the K value changes. Knowledge about genetic diversity and population structure of indigenous goats is essential for genetic improvement, understanding of environmental adaptation as well as utilization and conservation of goat breeds.

Dispersal patterns in black howler monkeys (Alouatta pigra): Integrating multiyear demographic and molecular data.

Dispersal is a fundamental process in the functioning of animal societies as it regulates the degree to which closely related individuals are spatially concentrated. A species' dispersal pattern can be complex as it emerges from individuals' decisions shaped by the cost-benefit tradeoffs associated with either remaining in the natal group or dispersing. Given the potential complexity, combining long-term demographic information with molecular data can provide important insights into dispersal patterns of a species. Based on a 15-year study that integrates multiyear demographic data on six groups with longitudinal and cross-sectional genetic sampling of 20 groups (N = 169 individuals, N = 21 polymorphic microsatellite loci), we describe the various dispersal strategies of male and female black howler monkeys (Alouatta pigra) inhabiting Palenque National Park, Mexico. Genetically confirmed dispersal events (N = 21 of 59 males; N = 6 of 65 females) together with spatial autocorrelation analyses revealed that the dispersal pattern of black howlers is bisexual with strong sex-biases in both dispersal rate (males disperse more often than females) and dispersal distance (females disperse farther than males). Observational and genetic data confirm that both males and females can successfully immigrate into established groups, as well as form new groups with other dispersing individuals. Additionally, both males and females may disperse singly, as well as in pairs, and both may also disperse secondarily. Overall, our findings suggest multiple dispersal trajectories for black howler males and females, and longer multiyear studies are needed to unravel which demographic, ecological and social factors underlie individuals' decisions about whether to disperse and which dispersal options to take.

La dispersión es un proceso fundamental en el funcionamiento de las sociedades animales, ya que regula el grado en que los individuos parentados se concentran espacialmente. El patrón de dispersión de una especie puede ser complejo ya que surge de las decisiones de los individuos conformadas por las compensaciones de costo-beneficio asociadas con permanecer en el grupo natal o dispersarse. Dada esta posible complejidad, la combinación de información demográfica a largo plazo con datos moleculares puede proporcionar información importante sobre los patrones de dispersión de una especie en particular. Basado en un estudio de 15 años que integra datos demográficos de seis grupos sociales con muestreo genético longitudinal y transversal de 20 grupos (N = 169 individuos, N = 21 loci de microsatélites polimórficos), describimos las diversas estrategias de dispersión de machos y hembras del mono aullador negro (Alouatta pigra) que habitan el Parque Nacional Palenque, México. Los eventos de dispersión confirmados genéticamente (N = 21 de 59 machos; N = 6 de 65 hembras), junto con los análisis de autocorrelación espacial revelaron que el patrón de dispersión de los monos aulladores negros es bisexual con fuertes sesgos sexuales en ambas tasas de dispersión (los machos se dispersan más a menudo que las hembras) y distancia de dispersión (las hembras se dispersan más lejos que los machos). Los datos de observación y genéticos confirman que tanto machos como hembras pueden inmigrar con éxito a grupos ya establecidos, así como formar nuevos grupos con otros individuos que se están dispersando. Además, tanto los machos como las hembras pueden dispersarse individualmente, así como en parejas, y ambos también pueden dispersarse secundariamente. En general, nuestros hallazgos sugieren múltiples trayectorias de dispersión para aulladores negros de los dos sexos, y se necesitan más estudios para desentrañar qué factores demográficos, ecológicos y sociales subyacen en las decisiones de los individuos sobre si dispersarse y qué opciones de dispersión tomar.

Broussonetia × hanjiana (Moraceae) microsatellite markers for species and ploidy determination developed using next-generation sequencing.

BACKGROUND: Broussonetia × hanjiana has been considered a hybrid owing to its morphology, which is intermediate between that of B. papyrifera (L.) L'Her. ex Vent. and B. kazinoki Siebold. A recent study demonstrated the hybrid origin of B. × hanjiana in Korea using molecular markers. In this study, we developed microsatellite markers for B. × hanjiana using next-generation sequencing and cross-species transferability analysis. METHODS AND RESULTS: A total of 432 primers were designed from 205,819 contigs. Among them, 24 microsatellite markers showing polymorphisms were used to evaluate the population genetic characteristics. The observed heterozygosity (HO) and expected heterozygosity (HE) were 0.835 and 0.628, respectively. The cross-species transferability of these markers was evaluated in two closely related species of Broussonetia; all 24 markers showed cross-species amplification. Using flow cytometry, diploid and triploid individuals were identified in B. × hanjiana. In particular, the BR137 marker showed evidence of two parent species (B. papyripera and B. kazinoki), with a hybrid pattern observed in B. × hanjiana, demonstrating its utility for species identification and ploidy assessment. CONCLUSIONS: The new B. × hanjiana microsatellite markers can be useful in genetic studies of closely related B. papyripera, B. kazinoki, and B. × hanjiana.

Development of a multiplex microsatellite marker set for the study of the solitary red mason bee, Osmia bicornis (Megachilidae).

BACKGROUND: Solitary bees, such as the red mason bee (Osmia bicornis), provide important ecosystem services including pollination. In the face of global declines of pollinator abundance, such haplodiploid Hymenopterans have a compounded extinction risk due to the potential for limited genetic diversity. In order to assess the genetic diversity of Osmia bicornis populations, we developed microsatellite markers and characterised them in two populations. METHODS AND RESULTS: Microsatellite sequences were mined from the recently published Osmia bicornis genome, which was assembled from DNA extracted from a single male bee originating from the United Kingdom. Sequences were identified that contained dinucleotide, trinucleotide, and tetranucleotide repeat regions. Seventeen polymorphic microsatellite markers were designed and tested, sixteen of which were developed into four multiplex PCR sets to facilitate cheap, fast and efficient genotyping and were characterised in unrelated females from Germany (n = 19) and England (n = 14). CONCLUSIONS: The microsatellite markers are highly informative, with a combined exclusion probability of 0.997 (first parent), which will enable studies of genetic structure and diversity to inform conservation efforts in this bee.

Development and characterization of novel microsatellite markers in Tilia amurensis Rupr. using next-generation sequencing.

BACKGROUND: Tilia amurensis (Malvaceae) is a deciduous broad-leaved tree distributed in Korea, China, and Japan. T. amurensis is used as a honey tree and also as a material for furniture, carving, and pulp. This study aimed to develop and characterize novel microsatellite markers using next-generation sequencing (NGS) of T. amurensis. METHODS AND RESULTS: NGS analysis using GS-FLX Titanium obtained 629,273 reads, of which 15,795 contigs were assembled with an average length of 830 bp. A total of 4774 microsatellite regions were detected in 3602 of 15,795 contigs. In total, 360 primer sets were designed based on the microsatellite regions. Among them, 15 primer sets were selected as reproducible polymorphic markers and were characterized for three populations of T. amurensis in Korea. The average number of alleles (NA) was 3.5 in Mt. Hambaek (HB), 3.7 in Mt. Odae (OD), and 3.8 in Mt. Sobaek (SB). The average observed heterozygosity (HO) and expected heterozygosity (HE) values were 0.497 and 0.370 in the HB population, 0.470 and 0.372 in the OD population, and 0.524 and 0.410 in the SB population, respectively. The average polymorphic information content (PIC) value of the 15 microsatellite markers was 0.686. CONCLUSIONS: The novel microsatellite markers will be useful for further studies on genetic diversity evaluation to conserve the genetic resources and natural populations of T. amurensis.

Population genetic structure of the malaria vector Anopheles fluviatilis species T (Diptera: Culicidae) in India.

Anopheles fluviatilis James (Diptera: Culicidae) represents a complex that comprises four sibling species (S, T, U, and V). Among these, species T is widely distributed in India. Chromosomal inversion polymorphism exists among different geographic populations of An. fluviatilis species T; however, population genetic structure is not understood. This study inferred a genetic structure among six geographically diverse populations of species T using a panel of microsatellite markers. Analyses indicated a significant but low genetic differentiation among the majority of the studied populations. A significant correlation was observed between genetic and geographic distances, exhibiting stepwise migration patterns among populations.

Analysis of the population genetic structure using microsatellite markers in goat populations in Taiwan.

Due to the poor growth rate of the Taiwan black (TB) goat in Taiwan, many exotic breeds were brought into breeding schemes to improve TB goat. However, the excessive cross-breeding of alien species with TB goat has decreased its population numbers, genetic variation and biodiversity. Therefore, TB goat population considered an endemic species in Taiwan that needed to be conservation. The objective of the present study was to analyze the genetic structure and TB goat using genetic markers for genetic improvement and to sustain germplasm conservation and utilization. 15 microsatellite markers, divided into three sets, were used to analyze 690 goats sampled from 10 goat populations. The average number of alleles (Na) and effective alleles (Ne) was 11.87 ± 3.93 and 5.093 ± 1.768, respectively. The average expected heterozygosity (HE) and observed heterozygosity (HO) was 0.780 ± 0.084 and 0.602 ± 0.116, respectively. The average polymorphic information content (PIC) was 0.747 ± 0.103; FIS was 0.058 ± 0.075. All 15 microsatellite markers were highly polymorphic. The genetic distances between individuals were estimated to construct a phylogenetic tree. In present study, the 690 goat samples were divided into 8 clusters. The results indicated that these 15 microsatellite markers successfully clustered goat populations in Taiwan and could assist in the preservation of TB goats.

Investigating genetic diversity and population phylogeny of five Chongqing local chicken populations autosomal using microsatellites.

The genetic diversity and population structures of five Chongqing local chicken populations were investigated using by 24 microsatellite markers. Results revealed that the mean number of alleles (NA) ranged from 7.08 (Daninghe chicken, DN) to 8.46 (Nanchuan chicken, NC). The highest observed heterozygosity (HO) and expected heterozygosity (HE) were observed in DN (HO = 0.7252; HE = 0.7409) and the lowest HO and HE were observed in XS (Xiushan native chicken [XS], HO = 0.5910 and HE = 0.6697). The inbreeding coefficient (FIS) within population ranged from 0.022 (DN) to 0.119 (XS). Among the 24 microsatellite markers, four loci (MCW0111, MCW0016, ADL0278, and MCW0104) deviated from the Hardy-Weinberg equilibrium in all the studied populations. The results of population polygenetic analysis based on Nei's genetic distance and STRUCTURE software showed that the clustering of the five populations was incomplete consistent with geographical distribution. Moreover, a large number of gene flows were widespread among different populations, suggesting that genetic material exchanges occurred due to human activities and migration which was also verified by PCoA. In summary, this study preliminarily showed that Chongqing local chicken populations had rich genetic diversity and remarkable genetic divergence, but still high risk in conversion. These findings would be useful to the management of conservation strategies and the utilization of local chicken populations in further.

Transcriptome-derived microsatellite markers for population diversity analysis in Archidendron clypearia (Jack) I.C. Nielsen.

BACKGROUND: The medicinal woody leguminous genus Archidendron F. Mueller serves as important herbal resources for curing upper respiratory tract infection, acute pharyngitis, tonsillitis, and gastroenteritis. However, genomic resources including transcriptomic sequences and molecular markers remain scarce in the genus. METHODS AND RESULTS: Transcriptome sequencing, genic microsatellite marker development, and population diversity analysis were conducted in Archidendron clypearia (Jack) I.C. Nielsen. Flower and flower bud transcriptomes were de novo assembled into 173,172 transcripts, with an average transcript length of 1597.3 bp and an N50 length of 2427 bp. A total of 34,701 microsatellite loci were identified from 26,716 (15.4 %) transcripts. Primer pairs were designed for 718 microsatellite loci, of which 456 (63.5 %) were polymorphic. Of the 456 polymorphic markers, 391 (85.7 %) and 402 (88.1 %) were transferable to A. lucidum (Benth.) I.C. Nielsen and A. multifoliolatum (H.Q. Wen) T.L. Wu, respectively. Using a subset of 15 microsatellite markers, relatively high genetic diversity was detected over two A. clypearia populations, with overall mean expected heterozygosity (He) being 0.707 and demonstrating the necessity of conservation. Relatively low differentiation between the two populations was revealed despite the distant separation (about 700 km), with overall inbreeding coefficient of sub-population to the total population (Fst) being 8.7 %. CONCLUSIONS: This study represents the first attempt to conduct transcriptome sequencing, SSR marker development, and population genetics analysis in the medicinally important genus Archidendron. Our results will offer valuable resources and information for further genetic studies and practical applications in Archidendron and the related taxa.

Development and characterization of Novel EST-based single-copy genic microsatellite DNA markers in white spruce and black spruce.

Due mainly to large genome size and prevalence of repetitive sequences in the nuclear genome of spruce (Picea Mill.), it is very difficult to develop single-copy genomic microsatellite markers. We have developed and characterized 25 polymorphic, single-copy genic microsatellites from white spruce (Picea glauca (Moench) Voss) EST sequences and determined their informativeness in white spruce and black spruce (Picea mariana (Mill.) B.S.P.) and inheritance in black spruce. White spruce EST sequences from NCBI dbEST were searched for the presence of microsatellite repeats. Forty-seven sequences containing dinucleotide, trinucleotide, tetranucleotide and compound repeats were selected to develop primers. Twenty-five of the designed primer pairs yielded scorable amplicons, with single-locus patterns, and were characterized in 20 individuals each of white spruce and black spruce. All 25 microsatellites were polymorphic in white spruce and 24 in black spruce. The number of alleles at a locus ranged from two to 18, with a mean of 8.8 in white spruce, and from one to 17, with a mean of 7.6 in black spruce. The expected heterozygosity/polymorphic information content ranged from 0.10 to 0.92, with a mean of 0.67 in white spruce, and from 0 to 0.93, with a mean of 0.59 in black spruce. Microsatellites with dinucleotide and compound repeats were more informative than those with trinucleotide and tetranucleotide repeats. Eighteen microsatellite markers polymorphic between the parents of a black spruce controlled cross inherited in a single-locus Mendelian fashion. The microsatellite markers developed can be applied for various genetics, genomics, breeding, and conservation studies and applications.

Genetic diversity and structure of landrace of lablab (Lablab purpureus (L.) Sweet) cultivars in Thailand revealed by SSR markers.

Lablab (Lablab purpureus (L.) Sweet) is a legume crop widely cultivated in tropical and subtropical regions of Africa and Asia. In this study, we assessed genetic diversity and population structure of 299 individuals of subspecies purpureus and bengalensis of lablab from Thailand using 13 simple sequence repeat (SSR) markers. The SSR markers detected only 34 alleles in total with a mean of 2.6 alleles per locus. Overall gene diversity was 0.360. Gene diversity (H E) and allelic richness (A R) in different geographic regions was comparable. Similarly, both H E and A R between subspecies purpureus and bengalensis were similar. STRUCTURE and neighbor-joining (NJ) analyses revealed that the 299 individuals were clustered into two major groups. In contrast, principal coordinate analysis (PCoA) revealed admixture of the lablab germplasm. STRUCTURE, NJ and PCoA analyses also revealed that the subspecies purpureus and bengalensis are not genetically differentiated. Although the number of individuals from the west of Thailand was small and all of them were collected from the same province, they possessed comparable gene diversity with those from the other geographic regions. These results demonstrated that there is moderately low genetic diversity of lablab in Thailand and the west of the country possesses high diversity of lablab.

Development and Characterization of Novel Polymorphic Microsatellite Markers for Tapinoma indicum (Hymenoptera: Formicidae).

Tapinoma indicum (Forel) (Hymenoptera: Formicidae) is a nuisance pest in Asia countries. However, studies on T. indicum are limited, especially in the field of molecular biology, to investigate the species characteristic at the molecular level. This paper aims to provide valuable genetic markers as tools with which to study the T. indicum population. In this study, a total of 143,998 microsatellite markers were developed based on the 2.61 × 106 microsatellites isolated from T. indicum genomic DNA sequences. Fifty selected microsatellite markers were amplified with varying numbers of alleles ranging from 0 to 19. Seven out of fifty microsatellite markers were characterized for polymorphism with the Hardy-Weinberg equilibrium (HWE) and linkage disequilibrium (LD) analysis. All seven microsatellite markers demonstrated a high polymorphic information content (PIC) value ranging from 0.87 to 0.93, with a mean value of 0.90. There is no evidence of scoring errors caused by stutter peaks, no large allele dropout, and no linkage disequilibrium among the seven loci; although loci Ti-Tr04, Ti-Tr09, Ti-Te04, Ti-Te13, and Ti-Pe5 showed signs of null alleles and deviation from the HWE due to excessive homozygosity. In conclusion, a significant amount of microsatellite markers was developed from the data set of next-generation sequencing, and seven of microsatellite markers were validated as informative genetic markers that can be utilized to study the T. indicum population.

Do aspermic (parthenogenetic) Fasciola forms have the ability to reproduce their progeny via parthenogenesis?

Across Far East Asia, aspermic Fasciola forms are found endemically. They have abnormal spermatogenesis and oogenesis, and it is presumed that their progeny are produced parthenogenetically and clonally. Because of this, they are also termed parthenogenic Fasciola forms. Currently, there is no evidence that they do indeed reproduce parthenogenetically and clonally. In this study, the multilocus genetic type (MLG) in 12 microsatellite markers of adult flukes and their subsequent progeny larvae were analysed using two laboratory aspermic Fasciola triploid strains. The MLGs of adults and their larvae were identical for all markers evaluated, suggesting that these strains reproduce their progeny clonally. The deviation between theoretical and actual frequency within the larvae genotype of the Fh_6 locus resulted in the inability for self-fertilization within individual adult flukes. These findings strongly suggested that aspermic Fasciola forms reproduce their progeny by means of parthenogenesis, possibly gynogenesis.

Genetic diversity and population genetic structure in native Ethiopian donkeys (Equus asinus) inferred from equine microsatellite markers.

We investigated the genetic diversity and population genetic structure of six morphologically distinct Ethiopian donkey populations using 12 equine microsatellite markers. The donkey populations were Abyssinian (AB), Afar (AF), Hararghe (HA), Ogaden (OG), Omo (OM) and Sinnar (SI). Blood samples were collected from 180 genetically unrelated donkeys (30 individuals per population). Population genetic diversity estimates showed that total number and mean number of observed alleles, average observed and expected heterozygosity were 94, 5.208 ± 0.0229, 0.555 ± 0.023 and 0.588 ± 0.022, respectively. Highly significant deficiency in heterozygote was detected within the overall samples (FIS = 0.055 ± 0.021; P < 0.001). Though highly significant (P < 0.001), heterozygote deficiency within populations relative to total population was moderate (FST = 0.046 ± 0.016), suggesting a higher diversity within the populations (95.4%) than between populations. Various genetic distance estimation methods produced a similar topology of un-rooted dendrograms that grouped the overall Ethiopian donkeys into lowland (Ogaden, Omo and Sinnar) and highland (Abyssinian, Afar and Hararghe) genetic lineages. Likewise, Bayesian clustering analysis produced a similar pattern of clustering that was highly concordant with traditional donkey classification systems in Ethiopia.

Genetic diversity and population structure of Zymoseptoria tritici in Ethiopia as revealed by microsatellite markers.

Septoria tritici blotch (STB), caused by Zymoseptoria tritici (formerly: Mycosphaerella graminicola or Septoria tritici), is one of the most devastating diseases of wheat globally. Understanding genetic diversity of the pathogen has supreme importance in developing best management strategies. However, there is dearth of information on the genetic structure of Z. tritici populations in Ethiopia. Therefore, the present study was targeted to uncover the genetic diversity and population structure of Z. tritici populations from the major wheat-growing areas of Ethiopia. Totally, 182 Z. tritici isolates representing eight populations were analyzed with 14 microsatellite markers. All the microsatellite loci were polymorphic and highly informative, and hence useful genetic tools to depict the genetic diversity and population structure of the pathogen. A wide range of diversity indices including number of observed alleles, effective number of alleles, Shannon's diversity index, number of private alleles, Nei's gene diversity and percentage of polymorphic loci (PPL) were computed to determine genetic variation within populations. A high within-populations genetic diversity was confirmed with gene diversity index and PPL values ranging from 0.34 - 0.58 and 79-100% with overall mean of 0.45 and 94%, respectively. Analysis of molecular variance (AMOVA) revealed a moderate genetic differentiation where 92% of the total genetic variation resides within populations, leaving only 8% among populations. Cluster (UPGMA), PCoA and STRUCTURE analyses did not group the populations into sharply genetically distinct clusters according to their geographical origins, likely due to high gene flow (Nm = 5.66) and reproductive biology of the pathogen. All individual samples shared alleles from two subgroups (K = 2) evidencing high potential of genetic admixture. In conclusion, the microsatellite markers used in the present study were highly informative and thus, helped to dissect the genetic structures of Z. tritici populations in Ethiopia. Among the studied populations, those of East Shewa, Arsi, South West Shewa and Bale showed a high genetic diversity, and hence these areas can be considered as hot spots for investigations planned on the pathogen and host-pathogen interactions. Therefore, the present study not only enriches missing information in Ethiopia but also provides new insights into the epidemiology and genetic structure of Z. tritici in Africa where the agro-climatic conditions and the wheat cropping systems are different from other parts of the world. Such baseline information is useful for designing and implementing durable and effective management strategies.

Development of microsatellite markers in Betula costata (Betulaceae) by next-generation sequencing and cross-species transferability test.

This study was conducted to develop the first species-specific microsatellite markers in Betula costata. A total of 178 primers were designed from 95,755 contigs and screened in two B. costata populations sampled from Mt. Hwaaksan and Mt. Gyebangsan. A total of 16 polymorphic microsatellite loci were selected and used for population genetic characterization. The average values of observed heterozygosity (HO) and expected heterozygosity (HE) of the Mt. Hwaaksan population were 0.488 and 0.493, respectively. The average values of HO and HE in the Mt. Gyebangsan population were 0.492 and 0.481, respectively. The null allele frequency was less than 0.2 in all loci. No significant linkage disequilibrium was detected in all combinations of loci. In addition, 26 polymorphic markers were selected by cross-species transferability test to B. costata using the microsatellite markers developed in four other Betula species. The cross-species transferability of the microsatellite markers developed in B. costata was conducted in two other Betula species. The transferability was 75% in B. ermanii and 100% in B. davurica. Therefore, the microsatellite markers developed and characterized in this study were expected to be useful for further genetic studies in B. costata and related species in the genus Betula.